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Today's Topics:
1. Re: How to build a package? (Henk-Jan van Tuyl)
2. Re: How to build a package? (John M. Dlugosz)
3. Re: How to build a package? (Norbert Melzer)
4. Re: How to build a package? (Karl Voelker)
5. Re: why do classes require the type variable in type
signatures? (Peter Hall)
6. Re: How to build a package? (John M. Dlugosz)
7. Re: How to build a package? (Norbert Melzer)
----------------------------------------------------------------------
Message: 1
Date: Wed, 23 Apr 2014 15:01:14 +0200
From: "Henk-Jan van Tuyl" <[email protected]>
To: [email protected], "John M. Dlugosz"
<[email protected]>
Subject: Re: [Haskell-beginners] How to build a package?
Message-ID: <op.xers4culpz0j5l@ubuntu>
Content-Type: text/plain; charset=iso-8859-15; format=flowed;
delsp=yes
On Tue, 22 Apr 2014 20:52:04 +0200, John M. Dlugosz
<[email protected]> wrote:
> I used cabal unpack to get the source of a package to read. Now I want
> to make a change. How do I tell Haskell Platform to make that (the
> same way cabal knows how to) and do so with the provided files rather
> than downloading into temp.
> I got a package to work before using Leksah, but I'd like to do it
> directly since the cabal file is present and works just fine.
Go to the directory where the .cabal file is, and type
cabal install
without a package name.
> A related issue: what should I do about the local copy of a module name
> that is also installed? Can I make my project use that instead, without
> having to globally change the name in all the files?
You can use a GHC extension, to specify the package to use, see
http://www.haskell.org/ghc/docs/latest/html/users_guide/syntax-extns.html
look for
Package-qualified imports
Regards,
Henk-Jan van Tuyl
--
Folding@home
What if you could share your unused computer power to help find a cure? In
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us closer sooner. Watch the video.
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http://members.chello.nl/hjgtuyl/tourdemonad.html
Haskell programming
--
------------------------------
Message: 2
Date: Wed, 23 Apr 2014 11:43:17 -0500
From: "John M. Dlugosz" <[email protected]>
To: [email protected]
Subject: Re: [Haskell-beginners] How to build a package?
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 4/23/2014 8:01 AM, Henk-Jan van Tuyl wrote:
>
> Go to the directory where the .cabal file is, and type
> cabal install
> without a package name.
Ah, I see. I was looking for a makefile or something that was part of the
package.
But won't that "install" it, overwriting the normal one?
>
>> A related issue: what should I do about the local copy of a module name that
>> is also
>> installed? Can I make my project use that instead, without having to
>> globally change
>> the name in all the files?
>
> You can use a GHC extension, to specify the package to use, see
> http://www.haskell.org/ghc/docs/latest/html/users_guide/syntax-extns.html
> look for
> Package-qualified imports
>
> Regards,
> Henk-Jan van Tuyl
>
>
------------------------------
Message: 3
Date: Wed, 23 Apr 2014 18:59:34 +0200
From: Norbert Melzer <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] How to build a package?
Message-ID:
<ca+bcvsu5xmrpai9z72zwyy19g4fta3ibgdca+kk7t7gutrd...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Am 23.04.2014 18:44 schrieb "John M. Dlugosz" <[email protected]>:
>
> On 4/23/2014 8:01 AM, Henk-Jan van Tuyl wrote:
>>
>>
>> Go to the directory where the .cabal file is, and type
>> cabal install
>> without a package name.
>
>
> Ah, I see. I was looking for a makefile or something that was part of
the package.
You can consider the *.cabal file a Makefile describing the package.
> But won't that "install" it, overwriting the normal one?
Yes. But you could enter the cabal-file and change the name of the package.
There are ways to tell fh-wedel which package it shall use on compiletime.
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Message: 4
Date: Wed, 23 Apr 2014 12:36:18 -0700
From: Karl Voelker <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] How to build a package?
Message-ID: <[email protected]>
Content-Type: text/plain; charset=us-ascii
> On Apr 23, 2014, at 9:43 AM, "John M. Dlugosz" <[email protected]>
> wrote:
>
> But won't that "install" it, overwriting the normal one?
It would be a good idea to do all of this in a cabal sandbox.
-Karl
------------------------------
Message: 5
Date: Wed, 23 Apr 2014 21:27:55 +0100
From: Peter Hall <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] why do classes require the type
variable in type signatures?
Message-ID:
<caa6hak7_s5lrob3ppbitd5jb8xdttrbahpvyiy5atjov1rj...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Consider two instances of your class:
data Foo = Foo
data Bar = Bar
instance AlsoSpecial Foo where
-- This implementation *must* be constant True or False because
-- we don't constrain b at all, so it has to work for all b.
isAlsoSpecial b = True
instance AlsoSpecial Bar where
isAlsoSpecial b = False
Now what would you expect this to output?
isAlsoSpecial "hello"
Peter
On 23 April 2014 09:23, Dimitri DeFigueiredo <[email protected]>wrote:
> Hello All,
>
> Why does this compile
>
> class Special a where
> isSpecial :: a -> Bool
>
> whereas, GHC 7.6 complains about this
>
> class AlsoSpecial a where
> isAlsoSpecial :: b -> Bool
>
>
> This is the error message I get:
>
> The class method `isAlsoSpecial'
> mentions none of the type variables of the class AlsoSpecial a
> When checking the class method:
> isAlsoSpecial :: forall b. b -> Bool
> In the class declaration for `AlsoSpecial'
>
> My question is: Why must I use the type variable of the class declaration
> (i.e. *a*) in the type signature for the associated method? Is there a
> fundamental reason for this or is it just a GHC specific limitation? I
> didn't see a need for it when watching this video
>
> http://channel9.msdn.com/posts/MDCC-TechTalk-Classes-
> Jim-but-not-as-we-know-them
>
> that explains the translation that GHC does to turn type classes into core.
>
>
> Thanks!
>
>
> Dimitri
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://www.haskell.org/mailman/listinfo/beginners
>
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Message: 6
Date: Wed, 23 Apr 2014 22:59:59 -0500
From: "John M. Dlugosz" <[email protected]>
To: [email protected]
Subject: Re: [Haskell-beginners] How to build a package?
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 4/23/2014 11:59 AM, Norbert Melzer wrote:
>
> Yes. But you could enter the cabal-file and change the name of the package.
> There are ways
> to tell fh-wedel which package it shall use on compiletime.
>
What's fh-wedel? GOogle only turns up a university of applied sciences in
Germany.
Changing the name of the package would not change the name of the modules
inside it, or is
there a prefix I can add automatically or something?
------------------------------
Message: 7
Date: Thu, 24 Apr 2014 09:35:31 +0200
From: Norbert Melzer <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] How to build a package?
Message-ID:
<CA+bCVssGGMZ5hGo8-cu6+7yg+OpHH3K-E03txeFpyvrNK8VM=a...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Google is right on FH Wedel, however, what I really wanted to write was
ghci instead. Auto correction on my must have gone wild ;-)
Am 24.04.2014 06:01 schrieb "John M. Dlugosz" <[email protected]>:
> On 4/23/2014 11:59 AM, Norbert Melzer wrote:
>
>>
>> Yes. But you could enter the cabal-file and change the name of the
>> package. There are ways
>> to tell fh-wedel which package it shall use on compiletime.
>>
>>
> What's fh-wedel? GOogle only turns up a university of applied sciences in
> Germany.
>
> Changing the name of the package would not change the name of the modules
> inside it, or is there a prefix I can add automatically or something?
>
>
>
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://www.haskell.org/mailman/listinfo/beginners
>
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